/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 86136
 * Date: 2024-09-28
 * Time: 15:56
 */
public class UsePreorderAndInorderCreateTree {
    static class TreeNode {
        public int val;
        public TreeNode left;
        public TreeNode right;

        public TreeNode(int val) {
            this.val = val;
        }
    }
    public int preIndex;
    public TreeNode buildTree(int[] preorder,int[] inorder) {
        return buildTreeChild(preorder,inorder,0,preorder.length-1);
    }
    public TreeNode buildTreeChild(int[] preorder,int[] inorder,int inBegin,int inEnd) {
        if(inBegin > inEnd) {
            return null;
        }
        TreeNode root = new TreeNode(preorder[preIndex]);
        int rootIndex = findVal(inorder,inBegin,inEnd,preorder[preIndex]);
        preIndex++;
        root.left = buildTreeChild(preorder,inorder,inBegin,rootIndex-1);
        root.right = buildTreeChild(preorder,inorder,rootIndex+1,inEnd);
        return root;
    }
    public int findVal(int[] inorder,int inBegin,int inEnd,int val) {
        for (int i = inBegin;i <= inEnd;i++) {
            if(inorder[i] == val) {
                return i;
            }
        }
        return -1;
    }
}
